pd4dSize: PD4D Endo scaling tip can be autoclaved between 5-20 minutes at 134°C The PD4D are used to remove subgingival calculus and interdental calculus.Size: PD4D Endo scaling tip can be autoclaved between 5-20 minutes at 134°C The PD4D are used to remove subgingival calculus and interdental calculus.